Britain suffered its worst train crash in more than 15 years after a derailment in Scotland killed three people, including the driver, and left another six injured.

The Scotrail service was traveling from Aberdeen to Glasgow when it left the tracks at 9:43 a.m. on Wednesday near Stonehaven on the North Sea coast. While the cause is still to be determined, the train may have hit a landslide after Scotland experienced heavy rain and widespread flooding.

The six people who were injured were taken to the hospital for treatment, British Transport Police Chief Superintendent Eddie Wylie said in a statement, adding that their condition is “not believed to be serious.”

The force will work with Britain’s Rail Accident Investigation Branch and the Office of Rail and Road to establish how the Inter City 125 HST came to derail.

A major incident was declared and about 30 emergency service vehicles attended the scene, with aerial TV footage showing that two carriages had overturned, with another rolling down an embankment.

The crash marks the first fatal accident in the U.K. involving people on a train since 2007, when a Virgin West Coast Pendolino derailed at a faulty set of points in northern England, killing one woman on board.

The death toll is the highest since 2004, when a train driver, five passengers and a motorist died after an HST hit a car parked on a level crossing near Reading, west of London.

Photograph: Network Rail engineers and Police officers work near the scene of a train crash by Stonehaven in northeast Scotland on Aug. 12, 2020. Photo credit: Michal Wachucik/AFP via Getty Images.